There are currently two patching technologies for repairing tiny holes or punctures in inflatable articles such as bicycle inner tubes. One consists of a wet, i.e., solvent-based, adhesive patch technology. The other consists of a pressure sensitive adhesive patch technology. Although damaged bicycle inner tubes are typically patched in European countries, in the United States it is usually considered to be more cost effective and efficient to replace the inner tube rather than to patch it. This is particularly true when compared to using wet adhesive patch technology. Therefore, many cyclists in the United States carry a spare inner tube when touring. Pressure sensitive adhesive (PSA) patch technology has recently emerged as a replacement for wet adhesive patch technology; however, there are problems with current PSA patches that has limited their usefulness. For example, current PSA patches are not considered a long-term "fix." That is, air in an article such as an inner tube with a hole patched with a PSA patch can quickly leak, sometimes over a 24-hour period.
The solvent-based adhesive patching system typically consists of a relatively thick patch typically about 1.3 mm and a container of a solvent-based adhesive. This system is used to repair an inner tube by first cleaning and/or abrading the punctured area, applying the solvent-based adhesive, allowing the solvent to evaporate, applying the patch, and waiting 15-20 minutes before pressurizing the inner tube. The patch is typically made from a rubber such as neoprene rubber. A similar system includes a two-layer patch having a main body of vulcanized rubber and a thin layer of nonvulcanized rubber adhered thereto, and a container of a vulcanizing fluid or "cement." The "adhesive" is formed when the layer of nonvulcanized rubber is contacted with the vulcanizing fluid that reacts with the uncombined sulfur to fully cure the rubber. These patching systems are both inconvenient and time consuming, and can be user sensitive. Another problem with the solvent-based patching system is that the solvent can evaporate once the container has been opened leaving a useless container of dried adhesive.
The pressure sensitive patching system typically consists of a single-sided pressure sensitive patch that can be approximately 0.75-1.5 mm thick. Typically, such patches have a thick backing and a thin layer of pressure sensitive adhesive disposed on one side of the backing. The backings are typically at least about 0.75 mm thick and the adhesive layers are typically about 0.05 mm thick. The backings are typically made of opaque polyethylene foam or thick neoprene rubber. The adhesives are typically rubber-based or acrylic pressure sensitive adhesives. The thick patch is applied over a hole in an inner tube, for example, after abrading or cleaning the punctured area to remove talc or other powder from the inner tube. Because this patch is pressure sensitive, it overcomes the inconvenience and time consuming weaknesses of the solvent-based adhesive patch system. Current single-sided pressure sensitive patches can be user sensitive because of the pressure sensitive adhesive performance properties.
Furthermore, such patches are not generally useful for all types of bicycles, e.g., mountain bikes and touring bikes. Because touring bike tires are inflated to a higher pressure than mountain bike tires, more aggressive adhesives are needed for patching mountain bike tubes. That is, lower pressure mountain bike inner tubes require an adhesive with better peel and shear strength because of the lower amount of assistance to hold the patch in place from the pressure caused by contact between the tube and the tire.
Many patches for repairing bicycle inner tubes have beveled or feathered edges. This provides a patch with an extremely thin peripheral lip that resists distortion or deformation and lifting under conditions of stress. The centers of such patches are typically at least about 1.0 mm thick. However, such patches are only effective and desirable on tubes where the overall thickness does not affect the ride or wear of the tire, as a thick patch can bulge the tire causing premature localized wear. Although thin (e.g., about 0.05-0.13 mm) vinyl repair patches are available, they typically also have a very thin layer of an adhesive, which can have poor peel strength.
Thus, there is a need for an improved pressure sensitive adhesive patch. Particularly, there is a need in the bicycle industry for an improved pressure sensitive inner tube patch that can be easily applied in the field. Most inner tube patches on the market are either complicated, inconvenient, or only effective on certain types of tubes. Furthermore, they are not considered a long-term fix. A simpler, faster, more convenient, and effective patch that can function on touring bikes, mountain bikes, or both, for a longer period of time, is desired.